1. Field of the Invention
The invention relates to a method for monitoring the refrigerant level in an air conditioner, and more specifically, to a method for monitoring the refrigerant level in an air conditioner having a compressor with a high pressure refrigerant circuit and a low pressure refrigerant circuit.
2. Description of the Related Art
DE 44 01 415 C1 describes a generic method for monitoring the refrigerant level in an air conditioner, the air conditioner having a compressor subdividing the refrigerant circuit into a high-pressure side and a low-pressure side. The pressure and the temperature are measured on the high-pressure side at time intervals, an assigned temperature is determined using the measured pressure with the aid of a refrigerant-specific function, and a refrigerant undercooling value Uw which can be evaluated as a measure of the refrigerant level is determined by subtracting the measured temperature from the assigned one. At least during prescribable operating phases of the air conditioner, use is made for the purpose of assessing the refrigerant level of a maximum value Mw which is set at the start of these operating phases to the last determined undercooling value Uw and is set in the course of this operating phase to a respectively newly determined undercooling value when the latter is greater than the maximum value Mw present at the corresponding instant.
In the case of this type of method for monitoring the refrigerant level in an air conditioner, it is disadvantageous that given a low outside temperature in the range below 15.degree. C. the externally controlled compressor is driven at low par, with the result that the measured relative pressure on the high-pressure side is low. No result capable of further use is obtained in this range for the undercooling value determined therefrom.
The present invention is aimed at one or more of the problems identified above.